JPH02119967A - Coater of web - Google Patents

Abstract

PURPOSE:To accurately and quickly detect the change in a bead gap by providing a plurality of sensors for measuring the distance between a coater and a gas ejector and between the gas ejector and a web in the horizontal direction of the web in the web holding face part of the gas ejector. CONSTITUTION:When the distance between a web 3 and a gas ejector 11 and/or the distance between the web 3 and a coater 2 are changed by tension fluctuation of the web 3, jetting pressure fluctuation of the gas ejector 11 or pressure fluctuation of the evacuated chambers 7, 8, the change thereof is output accurately in a real time by the gap sensors 12, 13. The outputs of the sensors 12, 13 are stored in a memory 17 via a signal processing part 14 and an arithmatic processing part 15 and also a command is output to a driving means 16 and thereby the position of the second coater 2 is controlled in the optimum position. The web 3 whose double sides have been uniformly coated is conducted through a conduction part D2 and carried to a cooling stage and a drying stage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for floatingly supporting a web (band-shaped flexible support) and applying a coating liquid to an extremely uniform film thickness.

More specifically, it relates to a device that applies one or more coating liquids to the surface of a web of photographic material, etc., opposite to the surface to be coated, by continuously moving the surface of the web while floating and supporting it. The present invention relates to a web coating device suitable for double-sided coating.

[Conventional technology]

Conventionally, various means and methods have been known as techniques for coating both sides of a support.

For example, ■Method of coating one side of a support, gelling it, and then bringing the gelled side into direct contact with a support roll and continuously applying the coating to the opposite side (Japanese Patent Publication No. 48-44171)■Small A method is known in which the support is floated by ejecting gas from the curved surface of a roll having holes or slits, and the coating is applied by pressing the tip of a coater against the support (Japanese Patent Publication No. 17853/1983).

However, with the above conventional technology, even if there is slight dust or scratches on the support roll that supports the gelled surface, the gelled coating surface will be disturbed, and a part of the coating layer may be left on the roll. The same problem occurs even if the adhesive remains, and maintenance is extremely difficult.

(2) If the circumferential speed of the support roll deviates even slightly from the transport speed of the support, the gelled coating layer will be greatly disturbed.

In addition, the technology described in Japanese Patent Publication No. 49-17853,
■As the width of the support increases, the difference in the amount of floating in the center direction of the support increases, making it impossible to press the tip of the coating machine evenly against the support, making it difficult to obtain a uniform coating layer over the entire surface of the support. .

■There is no consideration given to the vibration of the support before and after the coating machine, which tends to cause uneven coating.

(2) Since the method involves pressing the coater against the coater, there is a drawback that the bead coating method, such as a slide hopper, which is commonly used for coating photographic light-sensitive materials cannot be applied.

For this reason, the present inventors installed a coater and a gas ejector at positions substantially facing each other across a continuously running support, and injected gas from the gas ejector toward the support. We have proposed and put into practical use a coating method and apparatus in which coating is carried out by the coater while floating and supporting the support by ejecting water (Japanese Patent Application No. 56-17580).
1).

[Problem to be solved by the invention]

In the above-mentioned conventional technology, it was completely unknown how the bead gap (distance between the coater and the web) changes during the coating process and how it affects the state of the coating film.

That is, when coating is carried out by floating and supporting the web with a gas jet: 1. It has been empirically known that the bead gap changes depending on various conditions such as the thickness, hardness, and tension of the web, and as a result, the state of the coating film also changes. Therefore, the position of the coater has been adjusted according to the type of web, but this method relies on the intuition of a skilled worker, and there is a problem in that quick and accurate adjustment cannot be made during web coating.

For this reason, it is impossible to avoid coating failures due to changes in the bead gap, which causes a decrease in productivity and yield.

In view of the above points, the first object of the present invention is to provide a web coating device that can accurately detect changes in the bead gap in real time.

A second object of the present invention is to provide a web coating device that can maintain an optimal coating state by changing the coater position as needed in response to changes in the bead gap.

(Means for Solving the Problems) In order to achieve the above object, the present invention disposes a coater and a gas jet at positions substantially opposite to each other across a continuously running web, and the gas jet is In a web coating device that performs coating with the coater while floating and supporting the web by jetting gas toward the web from a container, a web holding surface portion of the gas jet is provided between the coater and the gas jet. Sensors for measuring the distance between the ejector and the web are provided at a plurality of locations in the width direction of the web, so that changes in the bead gap can be directly detected in real time.

Further, the coater is provided with a drive means for moving the coater back and forth in accordance with the output of the sensor, thereby configuring a drive system that can automatically control the coater position in accordance with changes in the bead gap.

〔Example〕

The present invention will be described below with reference to an embodiment shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing one embodiment of the overall configuration of the coating device of the present invention, FIG. 2 is a horizontal sectional view showing the relationship among the gap sensor, coater, web, and gas ejector, and FIG.
The figure is a block diagram showing the configuration of the drive system, Figure 4 is a perspective view of the bead gap, Figure 5 is a sectional view showing another example of a gas jet, and Figure 6 is a gas jet using a porous body. It is a sectional view showing an example of a container.

In the figure, 1 is the first coater, 2 is the second coater,
The first and second coaters 1.2 are connected to the introduction section D of the web 3.
I and the derivation part D2 are provided in this order, respectively.

Further, the coater 1.2 has gushing slits la and lb, respectively.
, and 2a, 2b, S slits la, lb,
The coating liquid gushing out from 2a and 2b enables two-layer coating. That is, the first coater 1
The second coater 2 applies coating liquid to the front surface 3a of the web 3 near the introduction part D2, and the second coater 2 applies the coating liquid to the back surface 3b of the web 3 near the exit part D2, so that coating on both sides of the web 3 can be realized. has been done. The second coater 2 is equipped with rollers R or suitable sliding means, and can be moved forward and backward by a drive means 17, which will be described later.

The web 3 is supported in contact with the auxiliary roller 4 and carried into the introduction section, then it is supported in contact with the main roller 5 and goes around, passes near the first coater 1, and is coated on the surface 3a by the coater 1. After that, it is conveyed to the cold air zone 6.

Reference numeral 7.8 denotes a vacuum chamber, and the chamber 7.8 appropriately suctions a bead (coating liquid in a state of being cross-linked from the coater to the web surface) consisting of the coating liquid from each coater 1 and 2.
This is to stabilize the transfer of the coating liquid to the web surface. The chamber 7 is located below the bead gap B+ of the first coater 1, and the chamber 8 is located below the bead gap B+ of the second coater 2.

are provided at the bottom of each.

The cold air zone 6 is for cooling the coating liquid applied to the front surface 3a of the web 3 to promote gelation, and cools it by contacting and supporting the back surface 3b (uncoated surface) of the web 3. The conveying roller group 9 conveys the web 3 while conveying the surface 3 of the web 3.
A small hole (or) that cools the (already coated surface) by blowing cold air
A slit group 10 is provided. The temperature in the cold air zone 6 depends on the coating conditions (temperature of the coating solution, coating thickness, coating speed, etc.) and web running conditions (web temperature, web thickness, web running speed, etc.), but usually the cold air The temperature of the web 3 when it leaves the zone 6 and is conveyed to the second coater 2 is 2~
It is adjusted to be around 15°C.

Reference numeral 11 denotes a gas ejector, and the ejector 11 floats and supports the web 3 to protect the surface 3a (already coated surface) of the web 3.
The liquid is passed around near the second coater 2 to apply a coating liquid to the back surface 3b (uncoated surface). That is,
A large number of fine ejection holes F are arranged in the web-holding surface 11a of the outer shell of the gas ejector 11, and the gas in the ejector 11 is transferred to the web 3.
The web 3 is jetted toward the surface 3a, and the web 3 can be floated and conveyed while being coated by the coater 2 (
Figure 4).

12.12, - are web gap sensors, and the gap sensors 12.12, - are installed at multiple locations (
There are 4 locations in Figure 2). The sensor 12 is used to measure the gap between the surface of the gas jet 11 and the web 3, and uses a non-contact method to measure the gap between the web 3 and the gas jet 1.
1 interval can be measured. Although an optical distance sensor is used in this embodiment, a capacitive sensor, an ultrasonic sensor, or the like may also be used.

13.13, . . . - are coater gap sensors, and the sensors 13.13, .
They are provided at a plurality of locations in the width direction of the web 3 adjacent to. The sensor 13 is connected to the gas ejector 11 and the second coater 2.
In this example, an eddy current type distance sensor is used, but for example, a capacitive type sensor or a radiation type sensor can be used to measure the gap between the coater and the gas jet without damaging the web. Anything that can be measured is fine.

The outputs of the sensors 12 and 13 are processed by the signal processing section 14 and the arithmetic processing section 15, and then stored in the memory 16 as appropriate.

(2) 7 is a driving means, and the driving means 17 is the sensor 12.
This is for configuring a drive system that adjusts the position of the second coater 2 according to the output of the second coater 13, and consists of an electrically controllable servo motor device (FIG. 3). That is, the driving means 17 digitizes the output of the sensor 12.13 in the signal processing section 14, and then moves the position of the second coater 2 back and forth as appropriate in accordance with a command value calculated by a predetermined algorithm in the arithmetic processing section 15. This makes it possible to maintain the bead gap B2 in an optimum state. The driving means 17 may be configured to move back and forth using, for example, a voice coil type actuator or an electrostrictive actuator. Further, a plurality of driving means may be appropriately arranged to curve the application side edge of the coater 2 so as to control the bead gap B2.

The web 3, which has not been coated on both sides, is carried into the introduction section while being supported in contact with the auxiliary roller 4, goes around the vicinity of the first cork 1 while being supported in contact with the main roller 4, and is gushed out from the gushing slits la and lb. Two layers of coating liquid are applied to the surface 3a. Next, the web 3 is placed in the cold air zone 6
While receiving cold air from the small hole group 10, the material is conveyed in contact with the conveyor rollers 9 and cooled to around 2 to 15 degrees Celsius.
The gas is transported to the gas ejector 11. The second coater 2 coats the back surface 3b of the web 3, whose coated surface 3a is floated and supported on the web foaming surface 11a of the ejector 11. Here, the distance between the web 3 and the gas jet 11 and/or the distance between the web 3 and the coater 2 depends on various conditions such as tension fluctuations in the web 3, fluctuations in the jet pressure of the gas jet 11, or pressure fluctuations in the decompression chamber 7.8. When the distance of
The gap sensor 12.13 outputs the change accurately and in real time. Next, the output of the sensor 12.13 passes through the signal processing section 14 and the arithmetic processing section 15 to the memory 17.
At the same time, a command is output to the drive means 16 to control the position of the second coater 2 to the optimum position. However, the movement of the coater 2 is controlled within a range that does not exceed a predetermined speed and frequency, since rapid movement will adversely affect the coating. As a result, the bead gap B2 is always maintained in an optimal state regardless of changes in coating conditions. Then, the web 3 coated uniformly on both sides is led out from the lead-out section D2, cooled and
It is transported to the drying process and the double-sided coating process is completed.

The gas used for floating support in this invention is N2
Any material such as gas or air can be used as long as there is no safety problem, but air is most commonly used.

The coated web coated on the opposite side in the floating support section is then exposed to cold air on both sides in a non-contact state in a cold air zone (not shown) to gel the coated layer, and is then conveyed to a non-contact drying zone. . In this non-contact gelling area or non-contact drying zone, even if the substrate to be coated fluctuates (or vibrates) in a direction perpendicular to the traveling direction, it is absorbed by the floating support and does not propagate, resulting in a uniform It was found that coating is possible.

The web to be coated used in the present invention may be a plastic film such as polyethylene terephthalate or cellulose triacetate, or a web for photosensitive materials such as paper. There are no particular restrictions on the material that makes up the curved surface of the floating support part, and any material can be used as long as it can withstand the internal pressure of the hollow part, but brass steel or stainless steel with hard chrome plating on the surface is preferable. When providing a through hole as in the case, plastic materials such as Bakelite or acrylic resin can also be used in view of ease of drilling.

In carrying out the present invention, in order to prevent the gas from colliding with the gelled coating layer in the floating support section and preventing the coating layer from being disturbed by the dynamic pressure of this gas, it is necessary to The temperature of the coating layer is 2 to 15°C.
It is desirable to increase the gel strength of the coating layer.

Although the present invention has been described above, the embodiments of the present invention are not limited thereto, and the gas ejector has a continuous curved surface in order to maintain high static pressure in the gap with the web in the floating support part, and Any material may be used as long as it can eject gas and satisfies the conditions of the present invention, and it is necessary that the outer shape is roll-shaped or that the part that allows gas to pass from the inside of the gas ejector to the outside has a through hole. Instead, a coating device equipped with a gas ejector of another configuration may be used. For example, the shape of the gas ejector may be semi-cylindrical or elliptical, and as shown in FIG. 5, which shows another example of the gas ejector, only the floating support part has a curvature on the outer surface, and the other parts are flat. It is also possible to have a form composed of . On the other hand, the major role of the part that allows the gas supplied inside the gas ejector to pass to the outside is to allow the gas to pass through and to provide pressure loss. As long as this condition is met, any type of hole may be used, and in the case of a through hole, the shape may be round or polygonal, and as shown in Figure 6, a porous material such as sintered metal The outer shell of the gas ejector of the non-contact support part may be configured by the above-mentioned structure. Furthermore, instead of making the gas ejector hollow, it is also possible to construct the gas ejector from the gas inlet to the outer surface of the non-contact support part entirely from a porous body as described above.

As a method for coating one side and the opposite side of the web to be coated, conventionally known methods such as bead coating and extrusion coating can be used.

〔Effect of the invention〕

As described above, the present invention includes disposing a coater and a gas ejector at substantially opposite positions with a continuously running web in between, and ejecting gas from the gas ejector toward the web. In a web coating device that performs coating with the coater while floating and supporting the web, the distance between the coater and the jet and the distance between the jet and the web are measured on the web holding surface of the gas jet. Since the present invention is characterized in that a plurality of gap sensors are provided in the width direction of the web, the relationship between the bead gap and coating failure can be numerically grasped accurately and in real time. For this reason, if the output of the gap sensor corresponding to the web application position is stored in memory, defective locations on the product web can be easily estimated, which greatly contributes to quality control and yield improvement.

Furthermore, if the optimal coke position is determined by appropriately processing the output of the sensor, and the coater is moved by the driving means according to the command, the beat gap can always be controlled at the optimal interval, and the coating state can always be kept in the optimal state. can be maintained. As a result, various excellent effects can be achieved, such as stabilization of the coating process, improvement of coating quality, and automation of bead gap adjustment work.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the overall configuration of the coating device of the present invention, FIG. 2 is a horizontal sectional view showing the relationship among the gap sensor, coater, web, and gas ejector, and FIG.
The figure is a block diagram showing the configuration of the drive system, Figure 4 is a perspective view of the bead gap, Figure 5 is a sectional view showing another example of a gas jet, and Figure 6 is a gas jet using a porous body. It is a sectional view showing an example of a container. 1 - First coater 2 - Second coater 3 - Web 3a - Web front side 3b - Web back side 4... Auxiliary roller 5 - Main roller 6 - Cold air zone 7.8 - Decompression chamber 9 - Conveyance roller Group 10 - Slit group 11 - Gas ejector 11a... Web holding surface 11b - Non-web holding surface 12 - Web gap sensor 13 - Coater gap sensor 14 - Signal processing section 15 - Arithmetic processing section 16--Memory 17--Driving means Dl...Introduction section--Derivation section B+, Bz'-Bead gap F--Minute ejection hole P-Porous body Fig. 4 Figure Figure

Claims (2)

[Claims] (1) A coater and a gas jet are disposed at positions substantially opposite to each other across a continuously running web, and the gas is spouted from the gas jet toward the web, so that the web can be In a web coating apparatus that performs coating with the coater while supporting the web while floating, a sensor for measuring the distance between the coater and the jet and the distance between the jet and the web is installed on the web holding surface of the gas jet. A web coating device characterized by being provided at multiple locations in the width direction of the web coating device. (2) The web coating apparatus according to claim 1, wherein the coater is provided with a driving means for moving the coater back and forth in accordance with the output of the sensor.